def f(n):
    d=2
    while d*d<=n:
        if n%d==0:
            return False
        d+=1
    return True
        
        
d=['zero', 'one','two', 'three', 'four', 'five',' six','seven', 'eight',' nine']
a=input().split()
if len(a)!=3 or a[0] not in d or a[1] not in d or a[2] not in d:
    print('Wrong input')
else:
    n=int(str(d.index(a[0])) + str(d.index(a[1])) + str(d.index(a[2])))
    for i in range(1,1000):
        if f(n-i):
            print(n-i)
            break
        if f(n+i):
            print(n+i)
            break